A first aspect of the invention relates to a treatment device for treating food products, in particular in mass production, with conditioned air, comprising a housing with a product inlet and product outlet, which housing defines at least one treatment chamber, at least one conveyor means for conveying the products through a treatment chamber from the product inlet to the product outlet, air-circulation means for causing an air stream to flow through a treatment chamber, and air-conditioning means for conditioning the air stream, which air-conditioning means at least comprise heating means and moisture-feed means.
A treatment device in the form of a cooking oven for the mass production of food products is known, for example, from WO 91/11660. This known oven comprises a housing which forms a cooking chamber. An endless conveyor, which extends along a helical conveying path from a lower entry of the housing to an upper exit of the housing, is arranged in this chamber. The conveyor has a supporting surface for carrying the food products, through which the treatment medium can pass. The oven is provided with the required conduits and a fan for causing air to circulate within the cooking chamber from the bottom of the helical conveyor past steam injection means and heating means back to the top of the helical conveyor. In one embodiment, the cooking chamber is divided into a top subchamber at a high pressure and a bottom subchamber at a lower pressure, by means of what is referred to as a mezzanine floor. To reduce problems with the heat balance in this embodiment of the oven resulting from the pressure difference between the entry and exit, in particular the expulsion of heated treatment medium or the ingress of air, at the entry and exit there are discharge chimneys interacting therewith for controlling the expulsion or intake of air and in this way to reduce heat loss and to keep the pressure in equilibrium at these positions, for safety reasons. These discharge chimneys can also be used to exchange some of the heated gaseous cooking medium for a supply of fresh air, in order to maintain the desired cooking conditions, in which context the use of a cooking medium which comprises undesirable flavours or the like is avoided in cooked food products. The section of the oven which is at a high pressure is preferably provided with a chimney in which is arranged an adjustable flap controlled by a servomotor for controlling the pressure. This chimney can also be used to periodically exchange a proportion of the used cooking medium for fresh medium.
Furthermore, U.S. Pat. No. 4,949,629 has disclosed a linear oven for cooking food products, which is divided into a number of zones each having separate cooking and heating chambers. In the zones, the humidity of the air can be controlled with the aid of a control device with a sensor, control unit and steam injection means.